<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <script src="vue.js"></script>
</head>
<body>
  <div id="app">{{content}}</div>
  <div>{{content}}</div>
  <script>
    var app = new Vue({
      el:'#app',
      data: {
        content: 'hello'
      }
    });

    setTimeout(function(){
      app.$data.content = 'hhhh'
    },1000);
  
  </script>

</body>
</html>